It is well know in motor vehicles to provide a side door assembly having a door window frame including an upper edge contiguous with the roof line of the vehicle. It is also well known to have the side window movable between a raised closed position and a lowered open position. The prior art discloses many curvature variations for movable side door windows including multidirectional curvatures attempting to effect a smooth transition between the window and the vehicle body.
In particular, it is highly desirable to have a transversely curved side door window which enables a smooth and rounded transition of the side door assembly into the vehicle roof for an aesthetically pleasing vehicle appearance. However, this desire for transverse curvature competes with the requirement that the side window must be vertically movable between the raised closed position and the lowered open position within the limited transverse dimensions of the side door structure.
In attempting to accomplish these competing objectives, the prior art has suggested side door windows having an upper stationary window and a lower movable window. The upper stationary window is either mounted at an angle or more highly curved than the lower window. However this arrangement has the shortcoming of requiring two pieces of glass, a seal and frame between the pieces of glass, and reducing the size of the window opening for the movable window.